Do electric lights affect our body clocks?

A new study into the effect of light suggests that the body's internal clock (or circadian rhythms) become skewed when they are exposed to electric lights. However, the mechanism reverts back to schedule when people pursue outdoor activities.

According to a new report, long-term exposure to electric lighting has altered humans’ circadian rhythms. However, a week of outdoor living, such as camping, can reset the internal body clock along the lines the 'nature' intended.

In people and animals circadian patterns follow a roughly 24-hour cycle, directed by the circadian control center of the brain. Another term for this is the 'internal clock', which functions as a mechanism to regulate daily patterns of behavior, such as sleep, appetite, and attention. These systems are very sensitive and are affected by daily changes of light and temperature.

The new insight came from a study of eight people. For the first week of the study, participants went about their ordinary routines at home. Next, they all went camping in the Rocky Mountains for a week without flashlights or electronics. Throughout the study, the participants wore wrist monitors that logged light intensity, time of day, and activity. Data was collected at the end of each week.

In a press release, Kenneth Wright, a University of Colorado Boulder integrative physiologist who led the study, said: "What’s remarkable is how, when we’re exposed to natural sunlight, our clocks perfectly become in synch in less than a week to the solar day."

Previous studies in animals have shown that when circadian rhythms go out of sync, health problems including obesity and metabolic disorders such as diabetes can arise. Moreover, studies of people who work night shifts have also revealed an increased susceptibility to diabetes.

The current study has been published in the journal Current Biology. The paper is titled "Entrainment of the Human Circadian Clock to the Natural Light-Dark Cycle".